Membranes:

Cutaneous Membrane:

Specialized Epidermal Cells:

Specialized Epidermal Cells Keratinocytes - waterproofs the skin
Melanocytes - produce melanin
Everyone has about the same number of melanocytes.

Skin Color:

Skin Color Genetic Factors
All humans have the same number of melanocytes
How much melanin they produce is controlled by several genes
Lack of pigment is called albinism
Environmental Factors
Exposure to sunlight

Tissue Layers:

Tissue Layers Epidermis
Upper layer of the skin
Dermis
Has a blood supply
Contains connective tissue and muscle
Attached to the body by a basement membrane

Epidermal Layers:

Epidermal Layers Stratum corneum - nuclei and organelles are destroyed by lysosomes and the cells fill with keratin
Stratum lucidum - only found in the palms and soles of feet
Stratum granulosum - cells start to become keritanized

Epidermal Layers:

Epidermal Layers Stratum spinosum - as these cells mature they lose the ability to divide
Stratum basale (germinativum) - the reproductive layer of the epidermis.
Push new cells to the surface

Dermis:

Dermis 1-2 mm thick, 3mm thick on the soles and palms
Skin is thicker in males than females

Dehydration:

Dehydration For exercise longer than 1 hour sports drinks are recommended to replace lost minerals
For exercise shorter than 1 hour plain water is as good as sports drinks
Drink 1 liter of water for every kilogram of mass lost after exercise

Healing Wounds:

Healing Wounds Inflamation
Blood vessels become more permeable and leak fluid around the site of the injury
Scabs form if blood vessels are broken

Healing Wounds (cont.):

Healing Wounds (cont.) Fibroblasts join the wound together
Granulation tissue may form over large wounds.